This invention relates in general to warning systems for emergency vehicles and, in particular, to improved warning systems employing a flash tube.
More specifically, but without restriction to the particular use which is shown and described, this invention relates to a light assembly having a flash tube, commonly known as a strobe light, used with a moving reflector for use in warning systems for emergency vehicles. The assembly of the invention is capable of scattering high intensity flashes of light over an enlarged area and attaining high optical gain.
It is common in the prior art to use a visually steady burning incandescent light in conjunction with moving reflectors to create high intensity flashes of light. The incandescent element generally provides a relatively small light source and operates favorably with the high optical gain provided by reflectors. Because of the steady nature of the light of an incandescent filament, the reflector can effectively be swept over limited arcs of rotation or oscillations, or through circles of 360.degree. to scatter the light over a greater area.
A strobe light, on the other hand, is a high intensity light device employing a gas filled tube capable of generating a flash intensity significantly greater than an incandescent bulb. Flash tube sources have been used in the prior art to create brief, high intensity flashes of light not requiring a moving reflector, since the flash tube creates its own flash. The light generated by a strobe device is generally broader in width than a incandescent bulb, since the light source is in the form of a tube. It has been known in the prior art to provide a 360.degree. strobe light by using it in combination with a stationary 360.degree. fresnel lens, although the efficiency of such systems is relatively low, being in the area of an optical gain of 5.
Flash lamp assemblies used in warning systems of emergency vehicles in the prior art have conventionally used a fixed reflector with a stationary strobe light. The reason that strobe lights have not been used previously with movable reflector systems is because of the nature of a gas discharge device. The flash tube is not continuous and provides a high intensity flash for a very brief time interval, after which the light is off. It has been undesirable to use a flashing strobe with a moving reflector, because the broad beam of the tube with its brief flash of high intensity would result in sections of an area being swept through movement of the reflector to be missed. This would result in areas in which observers would not see a visual flash, rendering the use of flash tubes with high gain moving reflectors inappropriate in situations, such as in emergency conditions.